Barbara Hogan (l) drank champagne with the activists
South African Aids campaigners have serenaded the new health minister and rejoiced at the departure of her controversial predecessor.
A group of activists sang outside the Cape Town flat of Barbara Hogan and drank champagne with her.
They have long called for the dismissal of Manto Tshabalala-Msimang, known as "Dr Beetroot" for her advocacy of healthy eating rather than drugs.
Some 5.5 million South Africans are HIV-positive.
This is more than in any other country in the world.
The government of former President Thabo Mbeki has long been criticised for not doing enough to distribute the anti-retroviral drugs that scientists say are the most effective way of combating Aids.
Dr Tshabalala-Msimang said the drugs were too expensive for South Africa and warned of possible harmful side-effects.
Manto Tshabalala-Msimang is now a minister in the president's office
Instead, she urged people with HIV to eat lots of garlic and beetroot.
Ms Hogan came down from her flat and drank champagne with the activists.
The Cape Times newspaper reported that Ms Hogan told the serenading activists she was "deeply touched".
South Africa's leading Aids lobby group, the Treatment Action Campaign (TAC), said Ms Hogan had been one of the few MPs to speak out on HIV/Aids during Mr Mbeki's time in office.
"She has a reputation for being hard-working, competent and principled," a TAC statement said.
"We believe that the period of politically supported AIDS denialism has ended," it said.
Ms Hogan spent eight years in prison in the 1980s for campaigning against the white minority apartheid government.
She has been an MP for the ruling African National Congress since apartheid was ended in 1994.
Aids Law Project attorney Fatima Hassan said the group was "ecstatic about the appointment of Barbara Hogan," the Sowetan newspaper reports.
"Manto Tshabalala-Msimang should have been replaced a long time ago," she said.
Mr Mbeki resigned on Thursday, to be replaced by Kgalema Motlanthe, who carried out a cabinet reshuffle.
Dr Tshabalala-Msimang was moved to become a minister in the president's office.